(1) Field of the Invention
This invention relates to a new method of imparting antibacterial activity to cellulosic textiles. More particularly, this invention relates to a new method of forming water-insoluble peroxide complexes of zirconyl acetate as deposits, films, and coatings on and within cellulosic fibers, yarns, and fabrics, as well as paper.
(2) Description of the Prior Art
While many types of antibacterial agents have previously been applied to cellulosic and non-cellulosic textiles, seldom have the products possessed a combination of strong activity against undesirable bacterial, together with high durability of antibacterial activity to repeated launderings. In many instances the antibacterial agents previously used have had undesired physiological side effects on contact with human skin or exposed tissue, or they adversely affected the color and feel of the textile, and in addition, were expensive to manufacture, as indicated by Gagliardi, American Dyestuff Reporter, P49-58 (Jan. 22, 1962).
The processes of the present invention utilize hydrogen peroxide and its inorganic derivatives as inexpensive reagents from which water-insoluble, colorless peroxide complexes of zirconyl acetate are formed on the cellulosic textile. It is hypothesized that the high moisture content of the cellulosic substrate interacts very gradually with the insoluble peroxide complexes of zirconyl acetate to give a slow but continual release of hydrogen peroxide and zirconyl ions from the fabric as the active antibacterial agents. Evidence for this hypothesis lies in the finding that although the peroxide complexes of zirconyl acetate can just as readily be formed on 100% polyester textiles as on cellulosic textiles, the treated polyester textiles are found to possess only slight antibacterial activity even at high measured peroxide contents. Since polyester textiles contain only small amounts of moisture, of the order of 5%-10% of that in cellulosic textiles at ordinary humidities, it appears that the available moisture content of the textile material is highly critical to the antibacterial activity of the treated material, as would be expected if water were needed to generate hydrogen peroxide by reaction with the insoluble peroxide complexes of zirconyl acetate. In any event, the much greater effectiveness of the present antimicrobial treatment on cellulose than on polyester shows that the effectiveness of the present invention is neither obvious nor predictable from the known antiseptic properties of simple inorganic peroxides studied previously.
The methods of forming peroxide complexes of zirconyl acetate on solid cellulosic materials, as developed in this invention, are also novel. The prior art suggests no method whereby the complexes can be kept in solution prior to and during their application to cellulosic textiles, but subsequently can be insolubilized on the textile material, thus being rendered durable to washing or leaching. The high durability of the antimicrobial activity imparted is a major advantage of the present invention over the processes of the prior art. It is well known that certain insoluble peroxides of zirconium can be formed by adding an alkali metal hydroxide to a mixture of a soluble zirconium salt and hydrogen peroxide in aqueous solution. It is also known that at very high acidities, aqueous solutions of zirconium salts interact with hydrogen peroxide to yield soluble peroxide complexes of zirconium. Neither of these processes is suitable for the treatment of textiles, or suggests any means of depositing the complexes in insoluble form on cellulosic substrates. The prior art on zirconium peroxides is reviewed by Blumenthal, "The Chemical Behavior of Zirconium," D. Van Nostrand Co., 1958, pp 198-200. Rot resistant finishes for cotton based on phenolic complexes of zirconium acetate were reported by Gonzales et al, Textile Res. J. 33, 600-608 (1963).
It has been well known for many years that hydrogen peroxide by itself is a safe and effective topical and oral antiseptic and disinfectant, when used in dilute aqueous solutions, and it can be used to cleanse open wounds. The present invention offers for the first time a means of bonding complexes of hydrogen peroxide to cellulosic textile, thus affording a new means of application of this antibacterial agent. Likewise, alkali metal perborates are known antiseptics but the prior literature furnishes no method for durably bonding them to cellulose. The prior art also discloses no means of bonding alkali metal peroxydiphosphates to cellulosic substrates.